fetus [fetuses]◼◼◼(an unborn or unhatched vertebrate showing signs of the mature animal) noun [UK: ˈfiː.təs] [US: ˈfiː.təs]The point at which an embryo becomes a fetus has apparently been chosen arbitrarily. = Le stade auquel un embryon devient un fœtus a apparemment été choisi arbitrairement.